Signaling system.



N o 756,719. PATENTBD APR. 5, 1904.

H. SHOBMAKER.

SIGNALING SYSTEM.

urmcunon Hum um. 1a, 1902.

no MODEL.

@Wtuoowo m (imam,

4:; ing in general UNITED STATES Patented April 5, 1904.

PATENT OFFICE.

HARRY SHOEMAKER, OF PHILADELPHIA,

DIRECT AND MESNE ASSIGNMENTS,

PENNSYLVANIA, ASSIGNOR, BY TO- INTERNATIONAL WIRELESS Y. GEHRING, OF PHILADELPHIA,

PENNSYLVANIA.

SIGNALING SYSTEM.

SPECIFICATION forming part of Letters Patent No.

Application filed gn: 19, 1902.

To all whmn it may concern/.-

Be it known that I, HARRY SHonMAKnn, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State 5 of Pennsylvania, have invented a new and useful Signaling System, of which the following is a specification.

My invention relates to electrical signaling, more especially that known as Wireless signaling, in which the energy representing the message or signal to be transmitted is modified by and in accordance with such message and impressed upon the natural media and received at the receiving-station from the natural media and employed to record a message, either audible or visible, by means of apparatus controlled by the arriving energy.

' My invention relates more particularly to the receiving-apparatus of such a system, and

depends for its principle upon that of the Wheatstone bridge, so commonly known in the electrical arts.

My invention comprises a method whereby a conductor of electricity which has either a great positive temperature coefiicient or a great negative temperature coefiicient is traversed by energy depending upon the received energy and when so traversed byelectrical energy increases or decreases its resistance,

and thereby throws out of balance a Wheatstone bridge, resulting in a flow ofcurrent from a source through the galvanometer-circuit of the bridge to operate a galvanometer, relay, or any other device.

My invention comprises a method for receiving wireless signals which depends upon the change of resistance of a conductor due to the heat produced in such conductor by the arriving energy or energy controlled by the 4 arriving energy traversing the conductor. For the conductor of great temperature coeflicient, either positive or negative, may be used a great variety of materials, those havingv high positive temperature coefiicients bemetals, and for such purposes iron, platinum, and the like may be used. I

- lay,

756,719, dated April 5, 1904.

Serial No. 120,175. (No model.) I

prefer platinum, however, especially in the case where I have it in the form of a very short and a very fine wire whereits temperature is apt to be considerable, for the purpose of preventing oxidation or destruction. It is to be understood that any substance having a great temperature coefiicient, either positive or negative, may be used, and the choice will depend upon the attendant circumstances. By an inspection of the table of the temperature coefiicients of the various substances those most suitable are readily found.

In the drawing, A represents the usual aerial conductor of a wireless signaling system, which connects atits lower end with one terminal of the substance having ahigh-temperature coefiicient, and which is represented by P. The other end of this member P is connected to earth-plate E. This member P forms, as clearly shown, one arm of a Wheatstone bridge, in the other arms of which are arranged resistances At R is shown the galvanometer or relay as located in the galv'anometer circuit,of the bridge. At B is shown a source of energy whose terminals connect to the bridge at the junction of resistances 1 and 2 and at the 1, 2, and 3, respectively.

junction of P and 3. Normally whenno message is being received the bridge is in balance, and there is no current flowing-through the galvanometer or relay R. However, when any radiant energy is received the temperature of the device P is increased,- with the con-- sequent increase or decrease in its resistance, according as its temperature coeflicient is positive or negative. In either event the bridge is thrown out of balance and a current will. flow through the galvanometer or relay R. The galvanometer may be used directly as the indicating instrument or, if R is a re- I circuit, telegraph systems-and-the it can be used to control a local as is customary in like.

a and b are choke-coils in the arms'll and respectively, of the bridge; 0 is another choke coil between the source B and the juncture of the arms P and 3 of the bridge. The purpose of these choke-coils is apparent, for they prevent any of the high-frequency oscillations received from going into undesired paths. The member P as I have used it has been a straight platinum Wire. It is to be understood, however, that the conductor P may he coiled up to save space or for any other reason. It is to be understood also that arelatively long conductor Pmay be used. Preferably a very short length is to be used with a crosssection which is very small indeed, so small, in fact, that the rise in temperature will be considerable, and thereby cause a corresponding change in the resistance of such wire.

What I claim is 1. The method of producing signals transmitted by electroradiant energy, which consists in transforming such radiant energy into the energy of electric currents, diverting said currents through one arm of a Wheatstone bridge, impeding the passage of such currents through the other arms of said bridge, transforming such energy of electric currents into the energy of heat, thereby unbalancing said bridge, and controlling a translating device in virtue of such heat energy.

2. The method of transmitting intelligence which consists in producing electroradiant energy, modifying such energy by and in accordance with the signal to be sent, convert ing such radiant energy into the energy of electric currents at the receiving-station, modi fying the resistance of one arm of a Wheatstone bridge in virtue of heat produced by such energy of the electric currents, impeding the passage of such currents through the other arms of said bridge, and producinga signal by such resistance change.

HARRY SHOEMAKER. Witnesses:

JOHN CoNNELL,

ALICE T. BURRoUGrr. 

